There are more than 1,300 known underground spaces in the area of Slovenský Kras karst, the highest number of caves within one area in Slovakia.

The most famous part of this national park is the Zádielská Tiesňava Gorge. During the winter counting of bats in the last two years, more than 30 new underground spaces were found.
Chiropterologists focused on finding new caves suitable for the wintering of the cool-philic species of bats, like common pipistrelle and parti-coloured bat.
Intense cave research is currently ongoing in this gorge.